1.General examination Check the naked (and corrected) distance and near visual acuity, external eye condition, refractive state, refractive interstitial, gaze nature and fundus condition, etc. 2.Ocular muscle examination In addition to the conventional eye muscle examination such as corneal reflection method, masking method and each diagnostic eye position, the following examinations should be performed: (1) Trigonometry plus masking method to check the original eye position, the strabismus degree when gazing directly above and below. (2) Retinal correspondence, fusion function, stereopsis, and determination of AC/A ratio. (3) Bimanual solid field examination to understand the range of gaze and to provide a basis for selecting the surgical method. (4) Hess screen to check the functional status of extraocular muscles. (1) If you have refractive error, you should wear corrective glasses during the examination. (2) When looking close, the patient should look at the small visual marker. To reduce the influence of adjustment factors on eye position, 3D lenses can be worn after the examination. (3) Measure the horizontal obliquity at 33cm and 6m gaze and the obliquity at up and down gaze respectively. (4) Most of the obliquity examined by the trigeminal plus cover method prevails, and the internal and external obliquity is examined by turning 25° angle upward or downward, some people think that turning 15° angle is enough (Duke-Elder), because the gaze position is too upward or too downward, which can easily cause false impression. (5) Pay attention to check the function of oblique muscle and rotational strabismus: ① the determination of the upper oblique muscle function is too strong, according to Parks classification method is divided into 4 levels, check the vertical obliquity when the eyes are turned down 30° and left, right 30°, the difference between the vertical obliquity of both eyes, A.1: <10°; B.2: 10° ~ 19°; C.3: 20° ~ 30°; D.4: >30°. ②The determination of excessive function of the inferior oblique muscle is divided into 3 levels according to the classification of Meng Xiangcheng: A.1 level (1 degree): that is, those who show upward strabismus when turning inward; B.2 level (2 degrees): those who show upward strabismus only when turning extremely inward; C.3 level (3 degrees): those who show upward strabismus only when turning inward and upward. (③) The determination of rotational strabismus was made by fundus camera photographic examination, and according to the Kong Lingyuan measurement method, the average value of normal optic disc-central concave angle was 7.381°, with a variation range of 1.429° to 13.333°, and the central concave was located 0.343 PD below the geometric central plane of the optic disc.